The long-term objective of the proposed project is to investigate whether or not the attentional, facilitatory, and inhibitory processes underlying word retrieval are impaired by different forms of brain damage. Specifically, the proposed project will focus on the extent to which the picture naming difficulties of patients with Alzheimer's Disease (AD) are influenced by impairments of the inhibitory processes that operate during word retrieval. Not only identifying, but understanding the nature of such an impairment would ultimately lead to changes in current diagnostic and compensatory treatment practices. The proposed project consists of two phonological priming experiments that will be administered to 24 young adults, 24 elderly adults, and 24 AD patients. The AD patients will be administered several tests to assess their visual-perceptual and lexical-semantic processing. Experiment 1 and 2 will manipulate prime type (phonologically related, phonologically unrelated, identity) and the time between primes and targets (100ms, 650ms). Experiment 1 will require a subject to name both the prime and target, and experiment 2 will require a subject to listen to the spoken name of the prime and name the target. The primary measure of interest for both experiments will be naming latency. The following results are expected for both the young and elderly controls. For experiment 1, a significant inhibitory priming effect (unrelated minus related naming latencies) and a significant facilitatory repetition priming effect (unrelated minus identity) should be obtained at both ISIs, although the effect should decrease from the 100ms ISI to the 650ms ISI. For experiment 2, if the inhibition that has been observed to occur when primes are named (exp. 1) operates at a phonological level in normals, then it should also operate when primes are heard. Moreover, the strength of this inhibition should decay over time. However, if facilitation (unrelated minus related) is observed only in experiment 2, the inhibition in experiment 1 can be associated with an output response process. Similar to experiment 1, a repetition priming effect is expected in experiment 2. For the AD patients, in experiment 1 they should show significantly less of an inhibitory priming effect than the normal elderly adults (and quite possibly facilitation) at both RSIs. However, they should show normal facilitatory repetition priming. For experiment 2, they should show consistent facilitatory priming (unrelated minus related) and repetition priming effects (unrelated minus identity) regardless of prime-target intervals.